The present invention relates to the production of polyurethane foams which may contain flame retardants and to compositions useful for the preparation of such foams.
It is known to produce polyurethane foams by reactions between polyisocyanates and polyhydroxy compounds in the presence of polyurethane foam producing catalysts, water as a blowing agent, and other components often including auxiliary blowing agents, particularly halogenated hydrocarbons. Such foams are produced in flexible, semi-rigid and rigid foams, and are employed for a wide variety of purposes. The chemistry of polyurethane foam production and the various applications of the foam products has been widely studied, is well known and need not be discussed in depth herein.
Industrial polyols useful for the preparation of polyurethane foams are generally polyethers or polyesters carrying reactive hydroxyl groups. The above-identified U.S. patent describes the use of carbohydrates including mono-, di-, oligo- and polysaccharides in place of industrial polyols and the use of mixtures of such carbohydrates and industrial polyols.
Pectin is a member of a special class of polysaccharides which have the ability to form gels with simple sugars and acid. The class includes other gel forming polysacchardes such as alginic acid and guar gum. The major chemical building block of pectin is galacturonic acid. The carboxylic acid groups of the galacturonic acid may be methylated, neutralized or free. The degree of methylation is normally used as a method of classifying various pectins. Some of the carboxyl groups may be neutralized with metallic ions such as sodium or calcium.
In pectic acid all of the carboxyl groups of the galacturonic acid are free. In pectinic acid some of the carboxyl groups are methylated, but none are neutralized. In pectin there is partial methylation and partial neutralization. All of these polysaccharides are useful in this invention and, for convenience, will be referred to herein as pectin. The invention will principally be described as it applies to pectin since this is the preferred reactant and readily available commercially. However, other gel forming polysaccharides such as alginic acid and guar gum can be similarly employed in the practice of the invention.